IL4 and Autoimmunity: These Th cells are further divided into subtypes, that is, the Th1 subset producing interferon (IFN) gamma that promotes cellular immune responses, the Th2 subset producing mainly interleukin-4 (IL-4), IL-13, and IL-5 to aid humoral immune responses, and the Th17 subset producing IL-17, which plays a crucial role in autoimmunity and allergen-specific immune responses.